US Secretary of State John Kerry and G7 foreign ministers on Monday called for a "world without nuclear weapons".

US Secretary of State John Kerry and G7 foreign ministers on Monday called for a "world without nuclear weapons", citing North Korea's sabre-rattling as a key challenge to achieving that goal.

"We reaffirm our commitment to seeking a safer world for all and to creating the conditions for a world without nuclear weapons in a way that promotes international stability," the group said in their "Hiroshima Declaration", after a landmark visit to the Japanese city's atomic bomb memorial.

"This task is made more complex by the deteriorating security environment in a number of regions, such as Syria and Ukraine, and, in particular by North Korea's repeated provocations," it added.

The G7 statement came as ministers wrap up their final day of meetings with discussions focused on global hotspot issues including terrorism and other security threats as well as instability in the Middle East, and the refugee crisis.